Registration Dossier
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EC number: 242-354-0 | CAS number: 18472-51-0
Bioaccumulation: aquatic / sediment
Administrative data
Link to relevant study record(s)
Description of key information
Results from experimental studies
An experimental study according to the recent guideline OECD 305 (2012) “Bioaccumulation in Fish: Aqueous and Dietary Exposure” or the EC method C.13 (Bioconcentration: Flow-through Fish Test) is not available.
However, results from non-guideline studies are available, which have been performed during the development of the test system and used for the previous OECD guideline. The results of these measurements have been published in peer-reviewed journals in 1982 and 1985. These papers give an overview of the bioconcentration potential of different chemicals using the same method in different studies. The accumulation of Chlorhexidine digluconate in Leuciscus idus melanotus was assessed in non Guideline tests 5 fish were exposed to ring-U-14C labelled Chlorhexidine in a concentration of 50 µg/L for 3 days. Based on radioactivity measurements, the bioaccumulation factor was determined to be 40 L/kg and 42 L/kg. In the first article the source of the nonlabelled material was clearly stated to be from ICI-Pharma Arzneimittelwerk, Heidelberg, Germany; additionally the specific activity of the labelled material was given. The test conditions have been published already in Korte et al (1978), and any deviations have been described in the later articles. These articles are overview articles and no detailed study reports, and thus information is limited. In addition, the method used does not completely fullfill the requirements of the current version of the OECD 305. Details on the methods used were limited in these studies, but results are consistent with what would be expected given the low experimental log Kow of 0.08 (ionized pH 5) and estimated log Dow range of -1.99 – 1.58 (at pH 7) for chlorhexidine (see below). Overall, the results can be used as supporting information that the bioaccumulation potential is low due to the relative low bioaccumulation factors received, especially if compared to the values obtained using the same method for clearly bioaccumulating substances published in the same article.
Key value for chemical safety assessment
- BCF (aquatic species):
- 42 L/kg ww
Additional information
Separation of the base chlorhexidine and gluconate is expected during uptake in fish. Therefore, probably the BCF of the free chlorhexidine was determined instead of the value of Chlorhexidine digluconate.
The result obtained in the experiment is higher than the calculated BCF value of 1.77 at pH 6-8.
Biomagnification via aquatic food chain is not expected.
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